Digital broadcast transmitter/receiver having an improved receiving performance and signal processing method thereof

ABSTRACT

A digital broadcast transmitting/receiving system, and a signal processing method thereof, includes a randomizer for randomizing a transport stream into a specified position of which stuff bytes are inserted, a stuff-byte exchanger for replacing the stuff bytes included in data output from the randomizer with specified known data, an RS encoder for performing an RS-encoding of data output from the stuff-byte exchanger, an interleaver for interleaving data output from the RS encoder, a trellis encoder for performing a trellis encoding of data output from the interleaver, an RS parity generator for generating a parity by performing an RS encoding of data output from the RS encoder, and outputting the generated parity to the trellis encoder, and a modulator/RF converter for modulating data output from the trellis encoder and performing an RF up-converting of the modulated data. The digital broadcast receiving performance can be improved even in an inferior multi-path channel by detecting the known data from the received signal and using the known data for synchronization and equalization in a digital broadcast receiver.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.11/475,098, filed Jun. 27, 2006, currently pending, which claimspriority from U.S. Provisional Patent Application No. 60/739,430, filedon Nov. 25, 2005 in the United States Patent and Trademark Office, thedisclosures of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

Aspects of the present invention relate to a digital broadcasttransmitter/receiver and a signal processing method thereof, and moreparticularly to a digital broadcast transmitter/receiver and a signalprocessing method thereof which can improve the receiving performance ofthe system by inserting a known sequence (also referred to as a“supplementary reference sequence (SRS)”) into a VSB (Vestigial SideBand) data stream and transmitting the data stream with the insertedknown sequence.

2. Description of the Related Art

An ATSC (Advanced Television Systems Committee) VSB system that is anAmerican-type digital terrestrial broadcasting system is a signalcarrier type broadcasting system, and uses a field sync signal in theunit of 312 segments. FIG. 1 is a block diagram illustrating theconstruction of a transmitter/receiver of an ATSC DTV standard as ageneral American-type digital terrestrial broadcasting system.

The digital broadcast transmitter of FIG. 1 includes a randomizer 110for randomizing Moving Picture Experts Group-2 (MPEG-2) transport stream(TS), and a Reed-Solomon (RS) encoder 120 for adding RS parity bytes tothe transport stream in order to correct bit errors occurring due to thechannel characteristic in a transport process. An interleaver 130interleaves the RS-encoded data according to a specified pattern. Atrellis encoder 140 maps the interleaved data onto 8-level symbols byperforming a trellis encoding of the interleaved data at the rate of ⅔.The digital broadcast transmitter performs an error correction coding ofthe MPEG-2 transport stream.

The digital broadcast transmitter further includes a multiplexer 150 forinserting a segment sync signal and a field sync signal into theerror-correction-coded data. A modulator/RF converter 160 inserts apilot tone into the data symbols into which the segment sync signal andthe field sync signal are inserted by inserting specified DC values intothe data symbols, performs a VSB modulation of the data symbols bypulse-shaping the data symbols, and up-converts the modulated datasymbols into an RF channel band signal to transmit the RF channel bandsignal. Accordingly, the digital broadcast transmitter randomizes theMPEG-2 transport stream, outer-codes the randomized data through the RSencoder 120 that is an outer coder, and distributes the coded datathrough the interleaver 130. Also, the digital broadcast transmitterinner-codes the interleaved data in the unit of 12 symbols through thetrellis encoder 140, performs the mapping of the inner-coded data ontothe 8-level symbols, inserts the field sync signal and the segment syncsignal into the coded data, performs the VSB modulation of the data, andthen up-converts the modulated data into the RF signal to output the RFsignal.

Meanwhile, the digital broadcast receiver of FIG. 1 includes a tuner(not shown) for down-converting an RF signal received through a channelinto a baseband signal, and a demodulator 210 for performing a syncdetection and demodulation of the converted baseband signal. Anequalizer 220 compensates for a channel distortion of the demodulatedsignal occurring due to a multi-path. A Viterbi decoder 230 correctserrors of the equalized signal and decodes the equalized signal tosymbol data. A deinterleaver 250 rearranges the data distributed by theinterleaver 130 of the digital broadcast transmitter. An RS decoder 250corrects errors, and a derandomizer 260 de-randomizes the data correctedthrough the RS decoder 250 and outputs an MPEG-2 transport stream.

Accordingly, the digital broadcast receiver of FIG. 1 down-converts theRF signal into the baseband signal, demodulates and equalizes theconverted signal, and then channel-decodes the demodulated signal torestore to the original signal.

FIG. 2 illustrates a VSB data frame for use in the American type digitalbroadcasting (8-VSB) system, into which a segment sync signal and afield sync signal are inserted. As shown in FIG. 2, one frame iscomposed of two fields. One field is composed of one field sync segmentthat is the first segment and 312 data segments. Also, one data segmentin the VSB data frame corresponds to one MPEG-2 packet, and is composedof a segment sync signal of four symbols and 828 data symbols.

In FIG. 2, the segment sync signal and the field sync signal are usedfor the synchronization and equalization in the digital broadcastreceiver. That is, the field sync signal and the segment sync signalrefer to known data between the digital broadcast transmitter andreceiver, which is used as a reference signal when the equalization isperformed in the receiver side.

As shown in FIG. 1, the VSB system of the American type digitalterrestrial broadcasting system is a single carrier system. Thus, thesystem has the drawback in that it is weak in a multi-path fadingchannel environment having the Doppler effect. Accordingly, theperformance of the receiver is greatly influenced by the performance ofthe equalizer for removing the multi-path fading.

However, according to the existing transport frame as shown in FIG. 2,since the field sync signal that is the reference signal of theequalizer 220 appears once for every 313 segments, its frequency isquite low with respect to one frame signal, and this causes theperformance of equalization to deteriorate. Specifically, it is not easyfor the existing equalizer 220 to estimate the channel using a smallamount of data as above and to equalize the received signal by removingthe multi-path fading. Accordingly, the conventional digital broadcastreceiver has the disadvantages that its receiving performancedeteriorates in an inferior channel environment, and especially in aDoppler fading channel environment.

SUMMARY OF THE INVENTION

An aspect of the present invention is to provide a digital broadcasttransmitter/receiver and a signal processing method thereof that canimprove the receiving performance of the system by generating andtransmitting a transport signal with known data added thereto in atransmitter side and by detecting the transport signal in a receiverside.

Additional aspects and/or advantages of the invention will be set forthin part in the description which follows and, in part, will be obviousfrom the description, or may be learned by practice of the invention.

According to an aspect of the present invention, a transmitter comprisesa randomizer for randomizing a transport stream into a specifiedposition of which stuff bytes are inserted, a stuff-byte exchanger forreplacing the stuff bytes included in data output from the randomizerwith specified known data, an RS encoder for performing an RS-encodingof data output from the stuff-byte exchanger, an interleaver forinterleaving data output from the RS encoder, a trellis encoder forperforming a trellis encoding of data output from the interleaver, an RSparity generator for generating a parity by performing an RS encoding ofdata output from the RS encoder, and outputting the generated parity tothe trellis encoder, and a modulator/RF converter for modulating dataoutput from the trellis encoder and performing an RF up-converting ofthe modulated data.

According to an aspect of the invention, the trellis encoder includes amemory for performing the trellis encoding, and performs a memoryinitialization with respect to data input in the position into which thestuff bytes are inserted.

According to an aspect of the invention, the trellis encoder outputs avalue for initializing the memory to the RS parity generator, receivesthe parity generated by the RS parity generator, and replaces acorresponding parity by the received parity.

According to an aspect of the invention, the digital broadcasttransmitter further includes a controller for generating a controlsignal that indicates information about the position into which thestuff bytes are inserted, and controlling the memory initialization ofthe trellis encoder.

According to an aspect of the invention, the controller transmitsposition information of the stuff bytes and the known data to bereplaced in the corresponding position to the stuff-byte exchanger, andtransmits position information of an initialization packet to the RSparity generator.

According to an aspect of the invention, the RS parity generatorincludes a packet buffer for temporarily storing a packet that includesan initialization area output from the RS encoder.

According to an aspect of the invention, the packet buffer receives andupdates data changed according to the memory initialization.

According to an aspect of the invention, the RS parity generator furtherincludes a byte mapper for mapping initialization symbols output fromthe trellis encoder with specified bytes, and outputting the mappedsymbols to the packet buffer, an RS encoder for performing an RSencoding of data output from the packet buffer, and a symbol mapper forconverting an output of the RS encoder into specified symbols.

According to an aspect of the invention, the stuff bytes are insertedinto an adaptation field of the transport stream.

According to an aspect of the invention, the information about aposition and a length of the stuff bytes is inserted in a specifiedposition of the transport stream.

In another aspect of the present invention, there is provided a signaltransmission method for a digital broadcast transmitter, which comprisesrandomizing a transport stream into a specified position of which stuffbytes are inserted, replacing the stuff bytes in the randomized datawith specified known data, performing an RS-encoding of data having thereplaced stuff bytes, interleaving the RS encoded data, performing atrellis encoding of the interleaved data, generating a parity byperforming an RS encoding of the RS encoded data, and outputting thegenerated parity for use in the trellis encoding, and modulating thetrellis encoded data and performing an RF up-converting of the modulateddata.

In still another aspect of the present invention, there is provided adigital broadcast receiver, which comprises a demodulator for receivingand demodulating a signal encoded by inserting specified known data intostuff bytes inserted into a specified position, an equalizer forequalizing the demodulated signal, a Viterbi decoder forerror-correcting and decoding the equalized signal, a deinterleaver fordeinterleaving output data of the Viterbi decoder, and a derandomizerfor performing a derandomization of output data of the deinterleaver.

In still another aspect of the present invention, there is provided atrellis encoder for a digital broadcast transmitter that transmitstransport stream formed by replacing stuff bytes inserted into aspecified position with specified known data, the trellis encodercomprising a memory for performing a trellis encoding, and performing amemory initialization with respect to data input in a position intowhich the stuff bytes are inserted.

In still another aspect of the present invention, there is provided adigital broadcast transmitter, which comprises a randomizer forrandomizing a transport stream into a specified position of which stuffbytes are inserted, a stuff-byte exchanger for replacing the stuff bytesincluded in data output from the randomizer with specified known data,an RS encoder for performing an RS-encoding of data output from thestuff-byte exchanger, an interleaver for interleaving data output fromthe RS encoder, a trellis encoder, including a memory, for performing amemory initialization with respect to data input in a position intowhich the stuff bytes are inserted, and performing a trellis encoding ofdata output from the interleaver; an RS parity generator for receiving avalue for initializing the memory, generating a parity, and outputtingthe generated parity to the trellis encoder, and a modulator/RFconverter for modulating data output from the trellis encoder andperforming an RF up-converting of the modulated data.

In still another aspect of the present invention, there is provided asignal processing method for a digital broadcast transmitter, whichcomprises randomizing a transport stream into a specified position ofwhich stuff bytes are inserted, replacing the stuff bytes in data outputin the randomization with specified known data, performing anRS-encoding of data output in the stuff-byte replacing, interleavingdata output in the RS encoding, performing a trellis encoding of dataoutput in the interleaving and performing a memory initialization withrespect to data input in a position into which the stuff bytes areinserted, performing RS parity generation by receiving a value forinitializing the memory, generating a parity, and outputting thegenerated parity for the trellis encoding, and modulating data output inthe trellis encoding and performing an RF up-converting of the modulateddata.

BRIEF DESCRIPTION OF THE DRAWINGS

These and/or other aspects and advantages of the invention will becomeapparent and more readily appreciated from the following description ofthe embodiments, taken in conjunction with the accompanying drawings ofwhich:

FIG. 1 is a block diagram illustrating the construction of atransmitting/receiving system of a general American-type digitalbroadcasting (ATSC VSB) system;

FIG. 2 is a view illustrating the structure of an ATSC VSB data frame;

FIG. 3 is a view illustrating the structure of a general MPEG-2transport stream packet;

FIG. 4 is a view illustrating the structure of an MPEG-2 transportstream packet that includes an adaptation field according to the presentinvention;

FIG. 5A to 5E are views illustrating diverse formats of an MPEG-2transport stream packet that includes an adaptation field to which stuffbytes are added according to aspects of the present invention;

FIG. 6 is a block diagram illustrating the construction of a digitalbroadcast transmitter according to an embodiment of the presentinvention;

FIG. 7 is a view illustrating the construction of a trellis encoder of adigital broadcast transmitter according to an embodiment of the presentinvention;

FIG. 8 is a block diagram illustrating the construction of an RS paritygenerator of a digital broadcast transmitter according to an embodimentof the present invention;

FIG. 9 is a block diagram illustrating an example of an RS paritygenerator of a digital broadcast transmitter according to an embodimentof the present invention;

FIGS. 10A to 10E are views explaining an SRS area of an interleaveraccording to an aspect of the present invention;

FIGS. 11A to 11B are views illustrating an input frame of an interleaveraccording to an aspect of the present invention;

FIGS. 12A to 12B are views illustrating an output frame of aninterleaver according to an aspect of the present invention;

FIGS. 13A to 13B are views illustrating an input frame of a repeatedstructure of an interleaver according to an aspect of the presentinvention;

FIGS. 14A to 14B are views illustrating an input frame of a stuff-byteexchanger according to an aspect of the present invention;

FIG. 15 is a block diagram illustrating the construction of a digitalbroadcast receiver according to an embodiment of the present invention;

FIG. 16 is a block diagram illustrating the construction of a digitalbroadcast transmitter according to another embodiment of the presentinvention;

FIG. 17 is a view illustrating the construction of a trellis encoderused in the transmitter of FIG. 16 according to an aspect of theinvention.

FIG. 18 is a flowchart provided to explain the operation of a digitalbroadcast transmitter according to an embodiment of the presentinvention; and

FIG. 19 is a flowchart provided to explain the operation of a digitalbroadcast receiver according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Reference will now be made in detail to the present embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings, wherein like reference numerals refer to the like elementsthroughout. The embodiments are described below in order to explain thepresent invention by referring to the figures. Also, well-knownfunctions or constructions are not described in detail since they wouldobscure the invention in unnecessary detail.

FIG. 3 is a view illustrating the structure of a general MPEG-2transport stream packet. Referring to FIG. 3, the general MPEG-2transport stream is composed of a TS header part of 4 bytes, and anadaptation field or payload data of 184 bytes. As shown, TS header partincludes an 8 bit sync byte, a 1 bit transport error indicator, a 1 bitpayload start indicator, a 1 bit transport priority indicator, a 13 bitpacket identifier (PID), a 2 bit transport scrambling control, a 2 bitadaptation field control, and a 4 bit continuity counter.

FIG. 4 is a view illustrating the structure of an MPEG-2 transportstream packet that includes an adaptation field to which stuff bytes areadded according to an aspect of the present invention. Referring to FIG.4, the MPEG-2 transport stream includes a header part of 4 bytes, anadaptation field of “n” bytes, and payload data of “184-n” bytes. Twobytes of the adaptation field include an adaptation field header (AFheader) including information about the length of the adaptation field.Stuff bytes that simply occupy a space without containing informationmay be inserted after the adaptation field header. Theexistence/nonexistence of the adaptation field is determined by thevalue of an adaptation field control bit in a TS header of the transportstream. Also shown is at 8 bit etc indicator or flag.

In an aspect of the present invention, an MPEG-2 TS packet in whichstuff bytes are inserted into an adaptation field of a transport streamsuch as a data format as illustrated in FIG. 4 is used as an input of atransmitter. FIGS. 5A to 5E are views illustrating diverse formats of anMPEG-2 transport stream into which a supplementary reference sequence(SRS) is to be inserted in order to implement the transmitter accordingto aspects of the present invention. Here, for convenience inexplanation, three bytes after a sync byte of the transport stream arecalled a normal header, first two types of the adaptation field arecalled an adaptation field (AF) header.

Generally, the SRS is a special known sequence in a deterministic VSBframe that is inserted in such a way that a receiver equalizer canutilize this known sequence to mitigate dynamic multi-path and otheradverse channel conditions. The equalizer uses these contiguoussequences to adapt itself to a dynamically changing channel. When theencoder states have been forced to a known Deterministic State (DTR) anappended pre-calculated “known sequence” of bits (SRS pattern) is thenprocessed immediately in pre-determined way at specific temporallocations at the Interleaver input of the frame. The resulting symbols,at the Interleaver output, due to the way the ATSC Interleaver functionswill appear as known contiguous symbol patterns in known locations inVSB frame, which is available to the receiver as additional equalizertraining sequence. The data to be used in transport stream packets tocreate these known symbol sequence is introduced into the system in abackward compatible way using existing standard mechanisms. This data iscarried in the MPEG2 adaptation field. Hence existing standards areleveraged, and compatibility is assured.

The RS Encoder preceding the Interleaver calculates the RS parity. Dueto resetting Trellis Coder Memory (TCM) encoders, the calculated RSParity bytes are wrong and need to be corrected. Thus an additionalprocessing step is involved to correct parity errors in selectedpackets. All packets with parity errors will have their RS parityre-encoded. A (52) segment byte interleaver with unique time dispersionproperties, that generates contiguous SRS pattern is leveraged to haveadequate time to re-encode parity bytes. Required time to do thisconstraints the maximum number of SRS bytes.

FIG. 5A shows the structure of an MPEG-2 packet data of a basic form ina VSB system using the SRS data as a training sequence. This MPEG-2packet data includes a normal header part (such as that shown in FIG. 3and FIG. 4) composed of a one-byte sync signal and a three-byte PID(Packet Identity), a two-byte adaptation field (AF) header includinginformation about the position of the stuff bytes, and stuff bytes of aspecified length N. The remaining bytes of the packet data correspond toa normal stream that is typical payload data. Since the start positionof the stuff bytes is fixed, the information about the byte position isexpressed by information about the length of the stuff bytes. Thestuff-byte length N may be in the range of 1 to 27. However, if thestart position is not fixed, it is understood that start positioninformation would be used.

FIGS. 5B to 5E illustrate packet structures having adaptation fields inwhich other information, such as a program clock reference (PCR), anoriginal program clock reference (OPCR), a splice countdown(splice_count), and the like, are included in order to effectively usethe SRS. In these cases, the adaptation field is constructed to have auniform size. A part except for the AF header and information such asPCR, OPCR, splice_count, and others, corresponds to the stuff bytes towhich the SRS is to be inserted.

FIG. 6 is a block diagram illustrating the construction of a digitalbroadcast transmitting system according to an embodiment of the presentinvention. Referring to FIG. 6, the digital broadcast transmitterincludes a randomizer 610, a stuff-byte exchanger 620, an RS encoder630, an interleaver 640, a trellis encoder 650, an RS parity generator660, a multiplexer 670, and a controller 680.

The randomizer 610 randomizes an input MPEG-2 transport steam data inorder to heighten the utility of an allocated channel space. The datainput to the randomizer 610 has the data format formed by insertingstuff bytes, which have a specified length of bytes, but does notinclude payload data as shown in FIGS. 5 a to 5 e, into a specifiedposition of the input transport stream data. The payload data includesaudio and/or video data, and can further include non AV data in otheraspects of the invention.

The stuff-byte exchanger 620 generates known data that is a specifiedsequence having a specified pattern prearranged between a transmitterside and a receiver side. The stuff-byte exchanger 620 replaces thestuff bytes in a stuff-byte position of the randomized data by the knowndata. The known data can easily be detected from payload data to betransmitted, and thus is used for synchronization and equalization inthe receiver side. In an aspect of the invention, the known data is SRSdata.

The RS encoder 630 adds a parity of specified bytes to the packet intowhich the known data is inserted by the stuff-byte exchanger 620 toreplace the stuff bytes in order to correct errors occurring due tochannels. The interleaver 640 performs an interleaving of the datapacket to which the parity output from the first RS encoder 630 is addedin a specified pattern.

The trellis encoder 650 converts the data output from the interleaver640 into data symbols, and performs a symbol mapping of the data symbolsthrough a trellis encoding method at the rate of ⅔. As shown, thetrellis encoder 650 initializes a value temporarily stored in its ownmemory device to a “00” state at the start point of the known data, andperforms the trellis encoding of the known data. However, it isunderstood that other states can be initialized at the start point.Also, the trellis encoder 650 outputs a value for initializing thememory to the RS parity generator 660, receives a new parity generatedby the RS parity generator, and replaces the corresponding existingparity by the received new parity.

The RS parity generator 660 generates a parity by performing an RSencoding of the MPEG-2 packet received from the RS encoder 630 using thevalue for initializing the memory received from the trellis encoder 650,and transmits the generated parity to the trellis encoder 650.

The controller 680 transmits position information of the stuff bytes andthe known data to be replaced in the corresponding position to thestuff-byte exchanger 620. Also, the controller 680 transmits theposition information of an initialization packet that includes a partused for the initialization among the packet of 187 bytes input to theRS parity generator 660 to the RS encoder 630, so that only theinitialization packet can be used. For convenience in design, under theassumption that 27 or 26 stuff bytes are used even if the stuff bytesthe number of which is smaller than 27 are used, 33 or 32 correspondinginitialization packets are used as an input of the RS parity generator660. However, it is understood that such an input need not be providedto the generator 660 in all aspects of the invention, and that othernumbers of initializations can be used as the input.

Also, the controller 680 outputs signals for indicating theinitialization area and parity area to be replaced to the trellisencoder 650. The trellis encoder 650 performs a memory initializationusing these signals, receives the parity generated by the RS paritygeneration unit 660, and replaces the existing parity by the receivedparity.

The multiplexer 670 inserts a segment sync signal into the dataconverted into the symbols by the trellis encoder 650 in the unit of asegment, and inserts a field sync signal into the data in the unit of afield as the data format of FIG. 2. A modulator and RF converter (notillustrated) performs a VSB modulation of a signal into which a pilotsignal has been inserted by performing a pulse shaping of the signal,carrying the pulse-shaped signal on an intermediate frequency (IF)carrier, and modulating the amplitude of the signal, performs an RFconversion and amplification of the modulated signal, and transmits anamplified RF-converted signal through a channel allocated with aspecified band.

Hereinafter, the construction and the operation of the trellis encoder650 of FIG. 7 will be explained in detail. The trellis encoder 650receives the initialization area and the parity area to be replaced fromthe controller 680, initializes the memory, and outputs the value usedfor the memory initialization to the RS parity generator 660. Since thetrellis encoder 650 has a feedback structure, its output is affected bythe previous memory value. Accordingly, if the memory values of thetrellis encoder 650 are not fixed although the stuff-byte exchanger 620has replaced the stuff bytes of the transport stream with specifiedknown data, the SRS of the known data may be output in various formsaccording to the memory value. In order to solve this problem, thememory of the trellis encoder 650 is initialized by changing an inputvalue of the trellis encoder 650 as large as the number of stuff bytesat an SRS start point.

FIG. 7 is a view illustrating the construction of a trellis encoder of adigital broadcast transmitter according to an embodiment of the presentinvention. If a memory initialization area for initializing the memorythat exists in a start position of the SRS is input to the trellisencoder 650, initial_sel operates under the control of the controller680, and a multiplexer (MUX) outputs a new value (X1′, X0′) (i.e., zeroforcing input) that makes the memory state “0” instead of an input (X1,X0) previously used in the trellis encoder 650. Here, since there aretwo memories in a convolutional encoder of the trellis encoder 650, twosuccessive symbols (i.e., 4 (=2*2)-bit input) are required in order toinitialize the memories.

Specifically, the input X1, X0 are input to corresponding multiplexerswith the initial_sel. The multiplexer corresponding to the input X1further received an output D1, and has an output with respect to whichan exclusive OR function is performed using the output D1. The result ofthe exclusive OR function is a mapping input Z2, which is stored in amemory S2 as a next value of the output D1. Once recalled from thememory S2, the output D1 is used as the new value X1′.

The multiplexer corresponding to the input X0 is multiplexed with areceived output D1, and the output of the multiplexer is a mapping inputZ1 and the new value X0′. An exclusive OR function is performed on themapping input Z1 using the output D1, and a result is stored in a memoryS1. The output of the memory S1 is the mapping input Z0, and is storedin a memory S0 to be recalled as the output D1.

Table 1 shows eight states of three memories S0, S1, and S2, and twosuccessive input values for making the memory state “0”.

TABLE 1 Present Input Next state/ Input Initial state t = 0 Presentstate t = 1 Next state Output select (S0, S1, S2) (X1, X0) (S0, S1, S2)(X1, X0) (S0, S1, S2) (z2, z1, z0) 1 0, 0, 0 0, 0 0, 0, 0 0, 0 0, 0, 0000 1 0, 0, 1 0, 1 0, 0, 0 0, 0 0, 0, 0 000 1 0, 1, 0 0, 0 1, 0, 0 1, 00, 0, 0 000 1 0, 1, 1 0, 1 1, 0, 0 1, 0 0, 0, 0 000 1 1, 0, 0 1, 0 0, 0,0 0, 0 0, 0, 0 000 1 1, 0, 1 1, 1 0, 0, 0 0, 0 0, 0, 0 000 1 1, 1, 0 1,0 1, 0, 0 1, 0 0, 0, 0 000 1 1, 1, 1 1, 1 1, 0, 0 1, 0 0, 0, 0 000

The trellis encoder 650 of FIG. 7 outputs X1′ and X0′ used for thememory initialization to the RS parity generator 660. Since new input(X1′, X0′) is used as an input of the trellis encoder 650, the parity ofthe MPEG-2 packet that includes the value (X1, X0) becomes an inaccurateparity. In order to form an accurate parity, the trellis encoder 650should construct the parity using the new input (X1′, X0′) instead ofthe existing input (X1, X0). The generation of the parity is performedthrough the RS parity generator 660. The parity newly generated by theRS parity generator 660 is sent to the trellis encoder 650, and thetrellis encoder 650 replaces the exiting parity by the newly generatedparity.

FIG. 8 is a block diagram illustrating the construction of an RS paritygenerator of a digital broadcast transmitter according to an embodimentof the present invention. Referring to FIG. 8, the RS parity generator660 includes a symbol-to-byte converter 810, a data deinterleaver 820, apacket buffer 830, an RS encoder 840, a data interleaver 850, and abyte-to-symbol converter 860. The symbol-to-byte converter 810 receivesan initialization symbol composed of two bits from the trellis encoder650, and performs a symbol-to-byte conversion. According to an aspect ofthe invention, the symbol-to-byte conversion is a reverse to the D.2byte-to-symbol table of the “ATSC Digital Television Standard” (documentA/53), the disclosure of which is incorporated by reference.

An example of the byte-to-symbol table is as follows:

Segment 0 Segment 1 Segment 2 Segment 3 Segment 4 Symbol Trellis ByteBits Trellis Byte Bits Trellis Byte Bits Trellis Byte Bits Trellis ByteBits 0 0 0 7.6 4 208 5.4 8 412 3.2 0 618 1.0 4 828 7.6 1 1 1 7.6 5 2095.4 9 413 3.2 1 617 1.0 5 829 7.6 2 2 2 7.6 6 210 5.4 10  414 3.2 2 6181.0 6 830 7.6 3 3 3 7.6 7 211 5.4 11  415 3.2 3 619 1.0 . . . . . . . .. 4 4 4 7.6 8 212 5.4 0 416 3.2 4 620 1.0 . . . . . . . . . 5 5 5 7.6 9213 5.4 1 417 3.2 5 621 1.0 . . . . . . . . . 6 6 6 7.6 10  214 5.4 2418 3.2 6 622 1.0 . . . . . . . . . 7 7 7 7.6 11  215 5.4 3 419 3.2 7623 1.0 . . . . . . . . . 8 8 8 7.6 0 204 5.4 4 408 3.2 8 612 1.0 . . .. . . . . . 9 9 9 7.6 1 205 5.4 5 409 3.2 9 613 1.0 . . . . . . . . . 1010 10 7.6 2 206 5.4 6 410 3.2 10  614 1.0 . . . . . . . . . 11 11 11 7.63 207 5.4 7 411 3.2 11  615 1.0 . . . . . . . . . 12 0 0 5.4 4 208 3.2 8412 1.0 0 624 7.6 . . . . . . . . . 13 1 1 5.4 5 209 3.2 9 413 1.0 1 6257.6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . 18 7 7 5.4 11  215 3.2 3419 1.0 7 631 7.6 . . . . . . . . . 20 8 8 5.4 0 204 3.2 4 408 1.0 8 6327.6 . . . . . . . . . 21 9 9 5.4 1 205 3.2 5 409 1.0 9 633 7.6 . . . . .. . . . 22 10 10 5.4 2 206 3.2 6 410 1.0 10  634 7.6 . . . . . . . . .23 11 11 5.4 3 207 3.2 7 411 1.0 11  635 7.6 . . . . . . . . . 24 0 03.2 4 208 1.0 8 420 7.6 0 624 5.4 . . . . . . . . . 25 1 1 3.2 5 209 1.09 421 7.6 1 625 5.4 . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 7 7 3.211  215 1.0 3 427 7.6 . . . . . . . . . . . . . . . . . . 32 8 8 3.2 0204 1.0 4 428 7.6 . . . . . . . . . . . . . . . . . . 33 9 9 3.2 1 2051.0 5 429 7.6 . . . . . . . . . . . . . . . . . . 34 10 10 3.2 2 206 1.06 430 7.6 . . . . . . . . . . . . . . . . . . 35 11 11 3.2 3 207 1.0 7431 7.6 . . . . . . . . . . . . . . . . . . 36 0 0 1.0 4 216 7.6 8 4205.4 . . . . . . . . . . . . . . . . . . 37 1 1 1.0 5 217 7.6 9 421 5.4 .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47 11 11 1.0 3227 7.6 . . . . . . . . . . . . . . . . . . . . . . . . . . . 48 0 127.6 4 216 5.4 . . . . . . . . . . . . . . . . . . . . . . . . . . . 49 113 7.6 5 217 5.4 . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . 95 11 23 1.0 . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . 96 0 24 7.6 . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . 97 1 25 7.6 . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . 787 11 191 1.0 . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . 788 0 192 7.6 . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . 789 1 199 7.6 . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . 815 11 203 1.0 3 419 7.6 7 623 5.4 11  827 3.2 . . . . . . . . . 8180 204 7.6 4 408 5.4 8 612 3.2 0 816 1.0 . . . . . . . . . 817 1 205 7.65 409 5.4 9 613 3.2 1 817 1.0 . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .827 11 215 7.6 3 419 5.4 7 623 3.2 11  827 1.0 . . . . . . . . .

The data deinterleaver 820 deinterleaves the symbol-to-byte convertedvalue, and then outputs the deinterleaved value to the packet buffer830. The packet buffer 830 temporarily stores a packet that includes theoutput of the data deinterleaver 820 and the initialization area in theunit of 187 bytes output from the RS encoder 630. The packet buffer 830replaces the value in the existing initialization area by a new value.In this case, all bits constituting one byte are not used as thereplaced input, but only four upper bits of the byte used for theinitialization are replaced. The RS encoder 840 performs an RS encodingof the output of the packet buffer 830, and adds the parity to theencoded output. Here, the parity generated by the RS encoder 630 passesthrough the data deinterleaver 820. The output of the data deinterleaver820 is byte-to-symbol-converted according to D.2 table of the “ATSCDigital Television Standard” (document A/53), and is used as an input ofthe trellis encoder 650.

FIG. 9 is a block diagram illustrating an example of a parity generator660 of a digital broadcast transmitter, which operates at high speed andsolves a delay problem occurring during the operation of the interleaver850 and the deinterleaver 820, according to an embodiment of the presentinvention. The parity generator 660 of FIG. 9 includes include a bytemapper 910, a packet buffer 920, an RS encoder 930, and a symbol buffer940.

The byte mapper 910 performs mapping of the initialization symbols inputfrom the trellis encoder 650 onto the byte-to-symbol-converted andinterleaved value, and outputs the mapped symbols to the packet buffer920. The packet buffer 920 temporarily stores a packet that includes theoutput of the byte mapper and the initialization area in the unit of 187bytes output from the RS encoder 650. After the data replacement isperformed in the packet buffer 920, the output of the packet buffer isRS-encoded by the RS encoder 930, and then is input to the trellisencoder 650 at high speed, through the symbol mapper 940. The symbolmapper 940 simultaneously operates the interleaver and thebyte-to-symbol converter of FIG. 8.

FIGS. 10A to 14B are views illustrating data formats for explaining anexample of the operation of the present invention. First, FIGS. 10A-10Eillustrate a view explaining the change of an SRS area of a transportstream according to an interleaving operation of the interleaver 640according to an aspect of the present invention.

The stuff bytes for the SRS that exist in 207 packets output from the RSencoder 630 according to the interleaving appear repeatedly in the unitof 52 segments. The stuff bytes are arranged in a horizontal directionaccording to the interleaving. Here, the first horizontal linecorresponds to the first stuff byte, the second horizontal line thesecond stuff byte, and the N-th horizontal line the N-th stuff byte,respectively. As illustrated in FIG. 2, the VSB frame has 312 datasegments arranged after a field sync segment. That is, since 312/52=6,six identical SRSs in the unit of 52 segments are arranged after thefield sync segment.

FIGS. 11A-11B show a view illustrating an SRS area, an initializationarea, and an initialization packet RS parity, as seen from the output ofthe RS encoder in the case where the length of the stuff bytes is 27.The initialization packet RS parity is a parity corresponding to theinitialization area, and indicates the parity to be replaced by a newparity according to the initialization of the trellis encoder. Asillustrated in FIGS. 10A-10E, a lower part of 52 bytes first appearsafter the interleaving, and this part becomes the initialization area.

One to 27 stuff bytes can be used for the SRS according to an aspect ofthe invention. When N stuff bytes are used for the SRS, up to N paritiescorresponding to the initialization area become the initializationpacket RS parities as shown in FIGS. 11A-11B. For example, if one stuffbyte is used, as shown in FIGS. 11A-11B, the initialization area of thefirst stuff byte has a size of 7 bytes, and seven packets 52, 1, 2, 3,4, 5, and 6 that include the initialization area are used for theinitialization. The initialization area of the second stuff byte has asize of 8 bytes, and packets 52, 1, 2, 3, 4, 5, 6, and 7 are used forthe initialization.

As illustrated, if N stuff bytes (i.e., the first stuff byte to the N-thstuff byte) are used to form the SRS, packets 52, 1, 2, 3, . . . , N+4,and N+5 correspond to packets that include the initialization area. Thatis, the parities of N+6 packets include the initialization area, theparities become the initialization packet RS parities, that will bereplaced later. If N=27, parities of the packets 52, 1, 2, 3, . . . ,31, and 32, i.e., 33 parities, become the initialization packet RSparities.

On the other hand, since a TCM encoder used in the ATSC performs atrellis encoding in the unit of 12 symbols, 12 TCM encoders should beinitialized for a complete initialization, but are not required in allaspects of the invention. However, due to causality, the first to fifthstuff bytes can initialize 7, 8, 9, 10, and 110 TCM encoders,respectively. Other stuff bytes used for the SRS can all be used for theinitialization. This number is equal to the size of the initializationarea of the respective stuff byte as illustrated in FIGS. 11A-11B. InFIGS. 11A-11B, since four symbols of the respective byte (two bits areused to construct one symbol) pass through the same TCM encoder, onebyte can initialize one TCM encoder. As described above, since theinitialization becomes possible with only two symbols, i.e., 4 (=2*2)bits, only four MSB bits of the initialization position are used for theinitialization, and four LSB bits are used to construct the SRS.

FIGS. 12A-12B show a view illustrating the data format of an output ofthe RS encoder 630 after the data passes through the data interleaver640. After the initialization area of 27 stuff bytes, paritiescorresponding to only 33 packets, i.e., packets 52, 1, 2, . . . , 31,and 32, appear. On the other hand, as described above, the output of thetrellis encoder 650 and the next memory state are affected by theprevious memory value. That is, if the previous input is changed, aninput to be used for the initialization is changed. If the parity of thepacket corresponding to the initialization area precedes theinitialization area, the input value previously used to initialize thememory of the trellis encoder 650 is changed due to the newly generatedparity. In this case, the initialization may not be performed, or anaccurate parity cannot be generated using the initialization value.Accordingly, in order to prevent the parity of the initialization packetfrom preceding the initialization area as shown in FIGS. 12A-12B, themaximum number of used stuff bytes becomes 27. However, it is understoodthat, for other types of packets divided into other numbers of segments,other maximum numbers of used stuff bytes can be imposed.

For the reason as described above, the trellis encoder 650 caninitialize up to seven first stuff bytes. The initialization positionsof the five remaining stuff bytes exist in the packets 47, 48, 49, 50,and 51, and since the parities of all the packets to be replaced precedethe initialization positions, parities cannot be used for theinitialization.

FIGS. 13A-13B show is a view illustrating the structure of a TS packetthat is repeated in the unit of 52 segments. In FIGS. 13A-13B, theoutput form of the RS encoder 630 in the case where 27 stuff bytes areused for the SRS is illustrated. If less than 27 stuff bytes are used,the initialization packet RS parities are reduced as much as a partcorresponding to the reduced area. Since the non-initialized part is notused for the SRS, it can be used for other purposes. In the drawing, ifthe PCR is transferred through the 15^(th) packet, it invades one byteof the SRS since it occupies a 6-byte space. In this case, thecorresponding space is not used for the SRS, and 6 bytes including thefront 5 bytes are used to transmit the PCR.

FIGS. 14A-14B show a view illustrating input values of a stuff-byteexchanger for generating the SRS according to an aspect of the presentinvention. The SRS pattern byte values are determined such that afterthe specific known data pass through the TCM encoders, the outputspecific known data has a spectrum similar to that of pseudo noise andhas an average DC (direct current) value close to 0. If less than 27stuff bytes are used, the replacement is performed as many as the numberof the stuff bytes. For example, if 10 stuff bytes are used, the SRS isgenerated in replacement of 10 corresponding parts. The lower four bitsof the initialization area are used for the SRS, while certain valuesmay enter into the upper four bits. Also, any value may enter into anon-initialized part. However, if the PCR is used, any other valuecannot enter into the PCR position so that the PCR is transferred as itis.

FIG. 15 is a block diagram illustrating the construction of a digitalbroadcast receiver according to an embodiment of the present invention.The digital broadcast receiver of FIG. 15 includes a demodulator 1510,an equalizer 1520, a Viterbi decoder 1530, a deinterleaver 1540, an RSdecoder 1550, a derandomizer 1560, and a controller 1570. A tuner (notillustrated) converts an RF signal received through a channel into abaseband signal, and the demodulator 1510 performs a sync detection anddemodulation of the converted baseband signal. While described in termsof a Viterbi decoder, it is understood that other decoders and/or symbolidentifiers can be used.

The equalizer 1520 compensates for a channel distortion of thedemodulated signal due to the multi-path of the channel. Also, theequalizer 1520 receives the known data (such as SRS) from the controller1570, and uses it for the channel distortion compensation. The Viterbidecoder 1530 error-corrects and decodes the equalized signal from theequalizer 1520. The deinterleaver 1540 rearranges the data dispersed bythe interleaver of the transmitter.

The deinterleaved data is error-corrected through the RS decoder 1550,and the error-corrected data is derandomized through the derandomizer1560, so that the data of the MPEG-2 transport stream is restored. Onthe other hand, the controller 1570 transmits the SRS period and valuesof the SRS to the equalizer 1520 to use them for the performanceimprovement. The SRS period and the values of the SRS are determinedaccording to the mode, and this mode may be predetermined or the modesignal may be transmitted from the transmitter. In the case where thetransmitter sends the mode signal, the controller 1570 detects the modesignal, and sends the SRS period and values of the SRS corresponding tothe mode to the equalizer 1520. In order to construct the SRS havingfixed values, its inputs should be determined as specified values asshown in FIG. 14. In order to improve the performance, the Viterbidecoder 1530 and/or the RS decoder 1550 receive accurate values of theSRS from the controller 1570 instead of the decoding output.

FIG. 16 is a block diagram illustrating the construction of a digitalbroadcast transmitter according to another embodiment of the presentinvention. The transmitter of FIG. 16 is a system that uses the linearcode characteristic of an RS encoder. An RS parity generator 1660 usesonly initialization symbols as its input. With respect to 187 bytesexcept for the initialization symbols, the RS parity generator 1660considers them as inputs of “0”, and outputs a parity. Specifically andreferring to FIG. 16, the digital broadcast transmitter further includesa randomizer 1610, a stuff-byte exchanger 1620, an RS encoder 1630, aninterleaver 1640, a trellis encoder 1650, a multiplexer 1670, and acontroller 1680. The randomizer 1610 randomizes an input MPEG-2transport steam data in order to heighten the utility of an allocatedchannel space. The data input to the randomizer 1610 has the data formatformed by inserting stuff bytes, which have a specified length of bytes,but does not include payload data as shown in FIGS. 5 a to 5 e, into aspecified position of the input transport stream data.

The stuff-byte exchanger 1620 generates known data that is a specifiedsequence having a specified pattern prearranged between a transmitterside and a receiver side. The stuff-byte exchanger 1620 replaces thestuff bytes in a stuff-byte position of the randomized data by the knowndata. The known data can easily be detected from payload data to betransmitted, and thus is used for synchronization and equalization inthe receiver side. The RS encoder 1630 adds a parity of specified bytesto the packet into which the known data is inserted by the stuff-byteexchanger 1620 in replacement of the stuff bytes in order to correcterrors occurring due to channels.

The interleaver 1640 performs an interleaving of the data packet towhich the parity output from the first RS encoder 1630 is added in aspecified pattern. The trellis encoder 1650 converts the data outputfrom the interleaver 1640 into data symbols, and performs a symbolmapping of the data symbols through a trellis encoding at the rate of ⅔.Here, the trellis encoder 1650 initializes the value temporarily storedin its own memory device to a “00” state at the start point of the knowndata, and performs the trellis encoding of the known data. Also, thetrellis encoder 1650 outputs a value for initializing the memory to theRS parity generator 1660, receives a new parity generated by the RSparity generator 1660, and replaces the corresponding existing parity bythe received new parity.

The RS parity generator 1660 generates a parity by performing an RSencoding of the MPEG-2 packet received from the RS encoder 1630 usingthe value for initializing the memory received from the trellis encoder1650, and transmits the generated parity to the trellis encoder 1650.The RS parity generator 1660 uses only initialization symbols as itsinput. With respect to 187 bytes except for the initialization symbols,the RS parity generator 1650 considers them as inputs of “0”, andoutputs the parity.

The controller 1680 transmits position information of the stuff bytesand the known data to be replaced in the corresponding position to thestuff-byte exchanger 1620. Also, the controller 1680 transmits theposition information of an initialization packet that includes a partused for the initialization among the packet of 187 bytes input to theRS parity generator 1660 to the RS generator 1660, so that only theinitialization packet can be used. For convenience in design, under theassumption that 27 or 26 stuff bytes are used even if the stuff bytesthe number of which is smaller than 27 are used, 33 or 32 correspondinginitialization packets can be used as an input of the RS paritygenerator 1660.

Also, the controller 1680 outputs signals for indicating theinitialization area and parity area to be replaced to the trellisencoder 1650. The trellis encoder 1650 performs a memory initializationusing these signals, receives the parity generated by the RS paritygeneration unit 1660, and replaces the existing parity by the receivedparity. The multiplexer 670 inserts a segment sync signal into the dataconverted into the symbols by the trellis encoder 1650 in the unit of asegment, and inserts a field sync signal into the data in the unit of afield as the data format of FIG. 2. A modulator and RF converter (notillustrated) performs a VSB modulation of a signal into which a pilotsignal has been inserted by performing a pulse shaping of the signal,carrying the pulse-shaped signal on an intermediate frequency (IF)carrier, and modulating the amplitude of the signal, performs an RFconversion and amplification of the modulated signal, and transmits anamplified RF-converted signal through a channel allocated with aspecified band.

FIG. 17 is a view illustrating the construction of a trellis encoder1650 used to perform the above-described operation. The trellis encoder1650 performs an exclusive OR of a new input bit required to initializethe memory and an input bit X0, X1 used as the original input in theinitialization area, and sends the result X1′, X0′ of the exclusive ORto an RS parity generator 1660. The RS parity generator 1660 generates aparity using this value only, and performs an exclusive OR of thegenerated parity and the parity input as the original input to bereplaced by the generated parity to use the resultant value of theexclusive OR. Accordingly, the same parity as the parity used to replacethe parity changed according to the initialization is input, and thesame operation is performed.

As shown, new RS parity from the RS re-encoder p0, p1 and the input bitsX0, X1 are input to the corresponding multiplexers 1200. An exclusive ORoperation is performed on the corresponding new RS parity p0, p1 priorto being received at the corresponding multiplexers 1200. According tothe initial select and the parity selection, the multiplexers 1200output D0s to corresponding multiplexers 1250.

For the output of the multiplexer 1250 corresponding to the parity p1and input bit X1, an exclusive OR operation is performed with respect toan output D1 of memory S2. The output D1 is further input to themultiplexer 1250. The result of the exclusive OR operation is a mappingoutput Z2 for use with a corresponding TCM. The mapping value Z2 is alsostored in the memory S2 as the next value for output D1. An exclusive ORoperation is performed with respect to the output D1 and the parity p1,and the result is output as new input X1′ used for the memoryinitialization to the RS parity generator 660.

The output of the multiplexer 1250 corresponding to the parity p0 andinput bit X0 is a mapping value Z1 for use with a corresponding TCM. Anexclusive OR operation is performed with respect to input bit X0 and themapping value Z1, and the output is the new input X0′ used for thememory initialization to the RS parity generator 660. An exclusive ORoperation is further performed on the mapping value Z1 with respect toan output D1 from a memory S0, and the result of the exclusive ORoperation is stored in memory S1 to be output as mapping output Z0 foruse with a corresponding TCM. The mapping output Z0 is stored in thememory S0 as the next value for output D1. The output D1 is furtherinput to the multiplexer 1250 with the output D0.

FIG. 18 is a flowchart provided to explain the operation of a digitalbroadcast transmitter according to an embodiment of the presentinvention. The randomizer 610 receives and randomizes an input transportsteam (S100). The stuff-byte exchanger 620 inserts the known data into astuff region included in the transport stream randomized by therandomizer 610, under the control of the controller 680 (S110).

When the transport stream into which the known data has been inserted isinput, the encoder 630 performs an RS encoding for adding a parity tothe parity area included in the transport stream packet (S120). Theinterleaver 640 performs an interleaving of the data packet, to whichthe parity output from the RS encoder 620 is added, in a specifiedpattern (S130). The trellis encoder 650 initializes the valuetemporarily stored in its own memory device at a start point of theknown data, and performs a trellis encoding of the known data (S140).

The RS parity generator 660 generates a parity by performing an RSencoding of the MPEG-2 packet received from the RS encoder 630 using thevalue for initializing the memory received from the trellis encoder 650,and transmits the generated parity to the trellis encoder (S150). Themultiplexer 670 inserts a segment sync signal into the data convertedinto the symbols by the trellis encoder 650 in the unit of a segment andinserts a field sync signal into the data in the unit of a field as thedata format of FIG. 2 (S160).

The modulator and RF converter (not illustrated) performs a VSBmodulation of a signal into which a pilot signal has been inserted byperforming a pulse shaping of the signal, carrying the pulse-shapedsignal on an intermediate frequency (IF) carrier, and modulating theamplitude of the signal, performs an RF conversion and amplification ofthe modulated signal, and transmits the amplified RF-converted signalthrough a channel allocated with a specified band (S170).

FIG. 19 is a flowchart provided to explain the operation of a digitalbroadcast receiver according to an embodiment of the present invention.The tuner (not illustrated) converts an RF signal received through achannel into a baseband signal, and the demodulator 1510 performs a syncdetection and demodulation of the converted baseband signal (S200). Theequalizer 1520 performs the equalization by compensating for the channeldistortion of the demodulated signal and removing the interferencebetween the received symbols (S210).

The Viterbi decoder 1530 error-corrects and decodes the equalized signal(S220). The deinterleaver 1540 rearranges the data dispersed by theinterleaver of the transmitter (S230). The deinterleaved data iserror-corrected through the RS decoder 1550 (S240), and theerror-corrected data is derandomized through the derandomizer 1560, sothat the data of the MPEG-2 transport stream is restored (S250).

As described above, according to an aspect of the present invention, thereceiving performance of the digital broadcast receiver such as thesynchronization and the equalization can be improved even in an inferiormulti-path channel by generating and inserting the stuff bytes into theMPEG-2 transport stream, and transmitting the transport stream intowhich the known data is inserted in replacement of the stuff bytes inthe digital broadcast transmitter, and by detecting the known data fromthe received signal and using the known data for the synchronization andthe equalization in the digital broadcast receiver.

According to an aspect of the present invention, the operationperformance of the equalizer can be improved through the properadjustment of the amount and the pattern of the sequence of the knowndata inserted into the transport stream, and thus the receivingperformance of the digital broadcast receiver can be improved.

Although a few embodiments of the present invention have been shown anddescribed, it would be appreciated by those skilled in the art thatchanges may be made in this embodiment without departing from theprinciples and spirit of the invention, the scope of which is defined inthe claims and their equivalents.

1. A digital broadcast receiver, comprising: a tuner to receive a streamfrom a digital broadcast transmitter; a demodulator to demodulate thestream; and an equalizer to equalize the demodulated stream, wherein thestream comprises an initialization byte which is used to initialize aTrellis encoding unit included in the digital broadcast transmitter. 2.The digital broadcast receiver as claimed in claim 1, furthercomprising: a decoder to decode the equalized stream; a deinterleaver torearrange the decoded stream; and an RS decoder to perform RS decodingof the rearranged stream.
 3. The digital broadcast receiver as claimedin claim 1, wherein the Trellis encoding unit comprises 12 Trellisencoders.
 4. The digital broadcast receiver as claimed in claim 1,further comprising: a controller to provide the equalizer with knowndata included in the stream.
 5. A stream processing method for a digitalbroadcast receiver, the method comprising: receiving a stream from adigital broadcast transmitter; demodulating the stream; and equalizingthe demodulated stream, wherein the stream comprises an initializationbyte which is used to initialize a Trellis encoding unit included in thedigital broadcast transmitter.
 6. The stream processing method asclaimed in claim 5, further comprising: decoding the equalized stream;rearranging the decoded stream; and performing RS decoding of therearranged stream.
 7. The stream processing method as claimed in claim5, wherein the Trellis encoding unit comprises 12 Trellis encoders. 8.The stream processing method as claimed in claim 5, wherein theequalizing comprises using known data included in the stream.